A fearsome looking predator

Thursday

Jun 29, 2017 at 12:01 AM

By Steve Lewka

There’s just something about predators. Perhaps it’s the sense of danger that often goes with them, or maybe it’s just that they seem more alert and intelligent than than prey animals. Whatever the case, they have fascinated me for a long time.

We met what may be, pound for pound – no, more like gram for gram - one of Iowa’s most fierce predators the other night. We had just returned from a short, but enjoyable, fishing trip out to Hickory Grove Lake. This hairy brown creature emerged from under my work bench as I prepared to clean a couple of nice, fat bluegills. Sue exclaimed that it looked like a tarantula, and it certainly did, at least with its nearly 3 inch leg spread. It wasn’t a tarantula, of course, but it was a female wolf spider, one of the largest spiders one will encounter in Iowa. I’m sure Sue would have been just as glad if I had stomped on it, but fascinated as I am with predators, I left it alone and watched it. It eventually went back under the work bench among the cans of nails, bolts and other things that come in handy from time to time. It’s also where tasty crickets, smaller spiders and other bugs might hide.

Wolf spiders are usually found in thicker cover outdoors and are usually most active at night. I say usually because they occasionally enter buildings looking for food and sometimes hunt in daylight. Their brown streaked coloration is good camouflage, but daylight hunting is dangerous for them because it’s more likely that they might become a meal for a bird. Unlike most spiders we’re used to seeing, they don’t spin webs to capture their food. Instead, they hunt from ambush or physically chase down their prey. They can move very quickly before they pounce on it, wrap their long legs around it, subdue it with a bite and eat it right on the spot – just like their wolf namesake. They use their excellent eyesight — with eight eyes arranged in three rows with four smaller eyes across the bottom, two larger eyes in the middle and two medium eyes on the top. They can also sense vibrations.

Wolf spiders have some other unusual habits. The mother may eat her smaller mate after he’s finished his job fertilizing the eggs. He would live less than a year anyway, but she might live several years. She only uses her spinnerets to create a silky sack for her eggs. She carries the sack with her until the spiderlings hatch and will search for it frantically if she loses it. The babies crawl onto their mother’s back after hatching and ride along with her for several days before venturing off on their own. That kind of care and nurturing of young is unusual in arthropods (spiders and insects).

You might also encounter a similarly large spider near streams and pond edges. These are fishing spiders or water spiders. They feed on larger aquatic insects, but also occasionally dive underwater to catch small fish and tadpoles. Neither of these large, fearsome-looking spiders are dangerous to humans. Although they’re not aggressive, they will bite if threatened. The bite might hurt and swell up, but is no more dangerous than other insect bites or stings. That’s not the case with central Iowa’s only truly poisonous spider, the slightly smaller brown recluse. A bite from that one can lead to ugly sores that are very slow to heal and where tissue actually dies. More detailed information on that will have to wait for another column, though.